Pot-type liquid fuel burners



.Feb. 18, 1969 JUlCHl HONDA ET POT-TYPE LIQUID FUEL BURNERS I ofP,

Sheet Filed Sept. 14, 1966 W. O 7 a 2 a o a 6 a r. 2 fig. y m ,A m A JIN VENT 0R3 Tue! Hanan ATTORNEY Feb. 18, 1969 JUICH] HONDA ET AL3,428,407

POT-TYPE LIQUID FUEL BURNERS Filed Sept. 1.4, 1966 Sheet 2 of 2INVENTORS JoueH Hon/0n K/m/o Maraumfin v snono Yasman levurneo M0!!!ATTORNEY United States Patent Office 3,428,407 Patented Feb. 18, 19693,428,407 POT-TYPE LIQUID FUEL BURNERS Juichi Honda, Kimio Matsumura,and Sadao- Yoshida,

Tochigi-ken, and Ryutaro Mori, Mitaka-shi, Japan, assignors to Hitachi,Ltd., Tokyo, Japan, a corporation of Ja an P Filed Sept. 14, 1966, Ser.No. 579,249 Claims priority, application Japan, Dec. 24, 1965,

40/79,301, 40/ 79,302, 40/ 79,303 US. Cl. 431-249 4 Claims Int. Cl. F23d/04 ABSTRACT OF THE DISCLOSURE A liquid fuel pot burner having a liquidcharged vaporizing plate with an outer cylindrical peripheral wallextending vertically therefrom, an open ended inner cylinder providingfluid communication through the center of the plate and being surroundedby an outer cylindrical cover provided in its lower portion with airsupply holes only within a quadrant thereof. An auxiliary burnerprovided with a wick is mounted radially opposite the air supply holesbetween the plate and a pilot ring, which is between upper secondary airsupply holes and lower primary air supply holes extending through theouter peripheral wall.

BACKGROUND OF THE INVENTION Pot-type burners of the type specified areprovided with a burner pot composed of a bottom plate in which a liquidfuel is to be charged and an outer peripheral wall upwardly extendingfrom the periphery of the plate and having air supply holes formedtherein, so that the liquid fuel introduced in the bottom plate isvaporized and mixed with air fed through the air supply holes forcombustion.

In this type of burner, the lower end of a kindling wick is dipped inthe liquid fuel introduced in the bottom of the burner pot to acceleratethe vaporization of fuel at the top thereof where the combustioninitially takes place.

The bottom of the burner pot is heated by the combustion of the fuel atthe kindling wick portion, thus accelerating the vaporization of fuelthereon and as a result the combustion is expanded from the combustionlocalized at the kindling wick portion over the entire surface of thebottom of the burner pot. The bottom of the burner pot is further heatedby the combustion of fuel over the entire surface thereof, with morefuel vaporizing thereon, and finally the combustion proceeds into normalcombustion.

When the combustion is not required, a small amount of fuel is burnt onan ignition wick which is provided as a substitution for the kindlingwick and thereby an automatic intermittent operation of the burner ispossible.

SUMMARY OF THE INVENTION An object of the present invention is toprovide a burner of the type which ensures complete combustion of a fuelduring normal operation of the burner with no generation of free carbonor soot and in which the combustion is stable even when the fuelquantity and/or draft are changed.

Another object of the invention is to provide a burner of the type inwhich transition of combustion from the combustion on an ignition wickor a kindling wick to normal combustion is effected smoothly.

Still another object of the invention is to provide a burner of the typein which generation of soot due to the combustion of a fuel on anignition wick or a kindling wick is minimized and a tolerable range offuel supply quantity is wide.

BRIEF DESCRIPTION OF THE DRAWING Other objects and advantages of thepresent invention will become apparent from the detailed descriptionprovided hereinafter with reference to the accompanying drawingsillustrating an embodiment thereof, in which:

FIG. 1 is a cross section through the axis of a pot-type liquid fuelburner according to the present invention;

FIG. 2 is a fragmentary cross section taken on the line A-A of FIG. 1;

FIG. 3 is a top view of the burner shown in FIG. 1; and

FIG. 4 is a perspective view in enlargement of an ignition or kindlingauxiliary burner of the inventive burner to illustrate the constructionthereof in detail.

DETAILED DESCRIPTION OF THE DRAWING The pot-type burner of the inventionhas a burner pot, which comprises a vaporizing plate 3 composing abottom and a lower portion of an outer peripheral wall of the burner, anouter peripheral wall 2 extending upwardly from said vaporizing plate 3and a combustion ring 1 mounted on the top end of said outer peripheralwall 2. The vaporizing plate 3 is formed at a portion of its outerperipheral wall with a fuel supply port 4 which is communicating with asuitable fuel supply source, e.g. a fuel tank. The bottom surface of thevaporizing plate 3 is sloped upwardly towards the center thereof. Thevaporizing plate 3 is also formed with an oil groove 18 at a portion ofthe bottom where the liquid fuel is first introduced through the fuelsupply port 4.

In the outer peripheral wall 2 of the burner pot are formed air supplyholes 6, 7, 8, 9, 10' and 11, of which 6 and 7 are directed upwardly forsupplying the secondary air therethrough; 8, 9 and 10 are directedhorizontally for supplying the primary air therethrough; and 11 isdirected downwardly for supplying the primary air therethrough.

Between said air supply holes 10 and 11 there is disposed a pilot ring25 whose outer diameter is slightly smaller than the inner diameter ofthe outer peripheral wall 2 of the burner pot and which rests on pins25a projecting inwardly from said outer peripheral Wall 2. An outercylindrical cover 13 is mounted at the center of the vaporizing plate 3to extend through a central opening 25b in said pilot ring 25 to a levelsubstantially equal to the level of said air supply holes 6 and 7. Theouter cylindrical cover 13 has formed in the entire periphery of the topend portion thereof secondary air supply holes 14, 15, 16 and 17 andalso formed in. a portion at most within a quadrant thereof below thepilot ring 25 air supply holes 20. An inner cylinder 12 having both endsopen is disposed interior of the outer cylindrical cover 13, with thebottom end thereof welded to the peripheral edge of a central opening3a, formed within a fitting for the outer cylindrical cover 13 providedon the vaporizing plate 3, in such a manner that the portion of the openended inner cylinder 12 projecting upwardly from the vaporizing plate 3is enclosed in the outer cylindrical cover 13.

The kindling wick or ignition wick 19 has its lower end dipped in theoil present in the oil groove 18, said wick 'being composed of aheat-resistant material, such as stainless steel, knitted into theshape. The air supply holes 20 are provided in opposed relation to theignition wick 19. The auxiliary burner comprising the ignition orkindling wick is formed of an upper partition wall 21 covering the topend of the wick 19 and side partition walls 35, 35, and is located belowthe pilot ring 25. The side partition walls 35, 35 are disposed radiallyto form an outwardly facing opening 22 in the proximity of the outerperipheral wall 2 of the burner pot, and have small holes 24 and 26formed in portions thereof. The ignition or kindling wick 19 is securedto the upper partition wall 21 by means of radially disposed guidemembers 23 and an ignition opening 5 is provided in the outer peripheralwall 2 in opposed .relation therewith.

With the construction described, air around the burner pot is constantlyintroduced into said burner pot through the air supply holes 6, 7, 8, 9,and 11 in the outer peripheral wall 2 and also through the open endedinner cylinder 12 and thence through the air supply holes 14, 15, 16,1-7, and in the outer cylindrical cover 13, by means of the draftproduced by a chimney or air blower.

When a small amount of liquid fuel is introduced through the fuel supplyport 4, the fuel flows in the oil groove 18 to soak into the wick 19 andis vaporized vigorously from the surface thereof. The fuel gas thusvaporized is mixed with air around the wick or the air supplied throughthe air supply holes 20, so as to be readily ignited through theignition opening 5.

The air introduced through the air supply holes 20 flows in the rightand left directions :and, by disposing the wick 19 at a point where saidflow of air is diverged, the wick may be ignite-d positively by alighted match through the ignition opening 5. This ignition may furtherbe ensured since said bidirectional flows of air are guided by guidemembers 23. The fuel combustion on the wick 19 elevates the temperatureof the liquid fuel present in the oil groove 18 to cause thevaporization thereof and thus the combustion is extended over the entirearea within the auxiliary burner. In this case, since the flame of theburning fuel on the wick 19 is directed towards the outer periphery ofthe burner, the vaporizing plate 3 is heated in an efficient manner,which will enhance the smooth extension of combustion in the auxiliaryburner. When the fuel is supplied in a small quantity, the comhustion inthe auxiliary burner takes place only in the vicinity of the small holes20 in the outer cylindrical cover 13, presenting the appearance as ifthe flames are injected through the small holes 20, but as the supply ofliquid fuel increases, the combustion moves in the direction in whichair is supplied through the holes 20, i.e. in the direction of the holes22, 22 in the auxiliary burner. Since, in this case, the flow of air fedthrough the holes 20 is diverged bidirectionally in the right and leftdirections, the combustion also proceeds in the right and leftdirections accordingly. The transition of such combustion is eased bythe guide members 23. As such, the transition of the combustion withinthe auxiliary burner may be optionally adjusted by the amount of liquidfuel supplied therein, and therefore the tolerable range of fuel supplyquantity is rendered wide. It is also to be noted that a uniform flow ofair into the auxiliary burner may be obtained by arranging the smallholes 20 in the outer cylindrical cover 13 in a symmetrical relationlateral ly and in uniformly spaced relation vertically as shown in FIGS.1 and 2, whereby the air is mixed with the fuel vaporizing on thesurface of the oil groove 18 homogeneously so as to minimize thegeneration of soot upon combustion. In addition, the side partitions 35,do not constitute 1. resistance to the combustion extending within theauxiliary burner because they are disposed radially with the interspaceexpanding progressively outwardly from the outer cylindrical cover 13towards the outer peripheral wall 3 and thereby it is possible to obtaina stable combustion without being subjected to disturbance. This alsocontributes to a stable combustion with a minimum soot.

The high temperature combustion gas generated in the auxiliary burnercontacts the outer peripheral walls 2, 3 of the burner pot to heat thevaporizing plate 3 at high efficiency. The vaporizing plate 3 may beheated most efliciently when the combustion takes place at the opening22 directly heating said plate. As a result, the vaporizing plate 3 canbe preheated in a short period of time. Therefore, when the liquid fuelis supplied in a large quantity thereafter, it is vaporized completelyand quickly from the entire surface of the vaporizing plate 3, providingfor a quick expansion of the combustion over the entire area of theburner pot. This combustion further heats the vaporizing plate 3 and asa result the combustion proceeds into normal combustion. It will beappreciated from the foregoing that, in the inventive burner, thetransition of combustion from the combustion on the ignition wick 19 tonormal combustion of the burner is effected in a highly satisfactorymanner.

The surface 26 of the vaporizing plate 3, as shown in FIG. 1, is slopedupwardly towards the center. This not only reduces the quantity of fueldumped thereon but also increases the strength of the plate. Stillfurther, the sloped surface enables the heat to be transmitted from theouter peripheral wall 2 to the oil effectively and provides for theformation of a uniform film of the oil thereon due to the surfacetension, which will promote the vaporization of the fuel and thus renderthe concentration of fuel gas uniform.

During normal combustion in the burner, a part of the primary air iscaused to flow through the open ended inner cylinder 12, disposed at thecenter of the burner pot, by the burning flame and discharged outwardlythrough the small holes 20 in the outer cylindrical cover 13 to beintroduced into the fuel gas vaporizing from the surface 26 ofvaporizing plate 3. That part of the primary air is then diverged to theright and left at the outer peripheral wall 2 and accelerates thevaporization of fuel together with the other part of the primary airintroduced through the air supply holes in the outer peripheral wall 2,producing a satisfactory mixture of the fuel gas and air.

In the embodiment illustrated herein, a part of the primary air, whichis introduced through the opening 22 of the auxiliary burner and flowsalong the outer peripheral wall 2, is caused to swirl centrally by theother part of the primary air being fed through the air supply holes 11in the outer peripheral wall, so that the fuel is mixed with the primaryair more thoroughly. Such a mixing of fuel gas and primary air takesplace below the pilot ring 25 which is sloped, most preferably at anangle of 15 The inner diameter of the pilot ring 25 is most critical forsatisfactory combustion of fuel and should therefore be determined so asto be optimum.

The resultant mixture of vaporized fuel oil and air, somewhat turbulent,then ascends through the space between the pilot ring 25 and the outercylindrical cover 13, during which period it is diluted progressivelyand homogeneously with the primary air supplied through the air supplyholes 10, 9 and 8, formed in the outer peripheral wall 2, in the ordermentioned. The mixed gas flows upwardly along the outer wall of theouter cylindrical cover 13 since said outer wall does not have holestherein and the primary air is supplied only unidirectionally from theouter peripheral wall 2 towards the center of the burner.

The gas thus mixed with air homogeneously thoroughly is further suppliedwith a large amount of the secondary air introduced through the smallholes 17, 16, 15 and 14 formed in the upper end portion of outercylindrical cover 13 and also through the small holes 7 and 6 formed inthe upper end portion of the outer peripheral wall 2, so that it burnscompletely with a short flame length while maintaining high combustiontemperatures. Even when there is some variation in the fuel ratesupplied and/or in the state of air draft, it is possible to obtain asatisfactory combustion constantly, owing to the thorough mixing of thefuel with the primary air and the supply of a large amount of thesecondary air as mentioned above. Accordingly the tolerable range of thefuel quantity is rendered wide and generation of free carbon or soot iskept to minimum.

The joint of the outer cylindrical cover 13 with the vaporizing plate 3is the area which is most critical relative to obtaining a satisfactoryproportion of the quantity of the primary air and the secondary airsupplied to the quantity of the fuel gas. In this view, the outercylinder is preferably connected to the vaporizing plate completely,either by means of welding or by the use of a heatresistant sealingmaterial, so as to ensure no air leakage therethrough. Such air-tightconnection may also be achieved by forming an upwardly extendingprojection 27 on the vaporizing plate 3 and a flange 28 at the bottomend of the outer cylindrical cover 13 as shown for scalable engagementwith each other.

The height of the open ended inner cylinder 12 should be determined suchthat a satisfactory proportion of the amount of air required for theignition combustion or the kindling combustion as will be describedlater to ,the amount of air required for normal combustion at high fuelrate can be maintained. A further minor adjustment may be effectedeither by changing the size of the guide members 23 or by the provisionof a metal net on said guide members.

In use of the pot-type burner described herein with a water-heater inwhich water is to be kept hot constantly, the burner is required to beoperated intermittently. Such intermittent operation may be achievedautomatically by using the ignition wick in place of the kindling wickand maintaining the combustion within the auxiliary burner by means ofthe kindling wick with the supply of low or pilot fuel rate when normalcombustion of the high fuel rate is not required. This combustionproceeds in the similar manner as in the case of ignition and it is,therefore, possibly to obtain a wide tolerable range of the fuel supplyquantity and to minimize the generation of soot.

It should be noted that, while the description herein is given on anembodiment, the present invention is not restricted thereto but manymodifications and changes are possible for the detailed portions withoutdeviating from the spirit and scope of the claims of the invention.

What is claimed is:

1. A pot-type liquid fuel burner having a burner pot, which potcomprising a vaporizing plate on which a liquid fuel is to be charged,an outer peripheral wall upwardly extending from the periphery of theplate and having a number of air supply holes formed therein, an openended inner cylinder vertically mounted on said vaporizing plate andcommunicating with the lower space below the plate and an outercylindrical cover upwardly extending from the upper surface of the plateand enclosing said inner cylinder and communicating with said innercylinder at the upper portion thereof, said outer cylindrical coverbeing imperforate in a lower portion thereof except within a quadrantthereof which is provided with holes for supplying air outwardlytherethrough towards the space between the outer cylindrical cover andsaid outer peripheral wall.

2. A pot-type liquid fuel burner having a burner pot, which potcomprising a vaporizing plate, an outer peripheral wall extending fromthe periphery of the plate and having formed therein a number ofsecondary air supply holes at the upper portion and a number of primaryair supply holes at the lower portion thereof, a pilot ring adapted todivide the interior of the burner pot vertically at a point below saidsecondary air supply holes, said burner pot being composed of saidvaporizing plate and said outer peripheral wall, an open ended innercylinder vertically mounted on said vaporizing plate and communicatingwith the lower space below the plate, and an outer cylindrical coverupwardly extending from the upper surface of the plate and enclosing aportion of said inner cylinder and communicating with said innercylinder at the upper portion thereof, said outer cylindrical coverbeing imperforate in a lower portion thereof except within a quadrantthereof which is provided with holes for supplying air outwardlytherethrough towards the space between the outer cylindrical cover andsaid outer peripheral wall and having secondary air supply holes at theupper end portion thereof.

3. A pot-type liquid fuel burner having a burner pot, which potcomprising a vaporizing plate for burning a liquid fuel thereon, aburner pot outer peripheral wall upwardly extending from the peripheryof the plate and having a number of air supply holes formed therein, anopen ended inner cylinder mounted on said vaporizing plate incommunication with the lower space below the plate thereof and an outercylindrical cover upwardly extending from the upper surface of the plateand enclosing a portion of said inner cylinder and communicating withsaid inner cylinder at the upper portion thereof, said outer cylindricalcover being imperforate in a lower portion thereof except within aquadrant thereof which is provided with holes for supplying airoutwardly peripherally therethrough, or a wick disposed within anauxiliary burner at a point where the air introduced through the holesin said outer cylindrical cover is diverted and having the lower endthereof dipped in the liquid fuel present in said vaporizing plate, saidauxiliary burner being composed of side partition walls extendingradially from both sides of the air supply holes in said outercylindrical cover towards the space between the outer cylindrical coverand said outer peripheral wall and defining an opening in the proximityof said outer peripheral wall and an upper partition wall covering thetop ends of said side partition walls, and an ignition opening formed insaid burner pot outer peripheral wall in opposed relation to said wick.

4. A pot-type liquid fuel burner having a burner pot, which potcomprises a vaporizing plate on which a liquid fuel is to be charged, aburner pot open ended outer peripheral wall upwardly extending from theperiphery of the plate and having a number of secondary air supply holesformed in the lower portion and a number of primary air supply holesformed in the lower portion thereof, a pilot ring adapted to divide theinterior of the burner pot vertically at a point below said secondaryair supply holes, said burner pot being composed of said vaporizingplate and said outer peripheral wall, an open ended inner cylindervertically mounted on. said vaporizing plate and communicating with thelower space below the plate, an outer cylindrical cover upwardlyextending from the upper surface of the plate and enclosing a portion ofsaid inner cylinder which is extending upwardly from said evaporatingplate and communicating with said inner cylinder at the upper portionthereof, said outer cylindrical cover being imperforate in a lowerportion thereof except within a quadrant thereof which is provided withholes for supplying air outwardly therethrough towards the space betweenthe outer cylindrical cover and said outer peripheral wall, a wickdisposed within an auxiliary burner at a point where the air introducedthrough the holes in said outer cylindrical cover is diverged and havingthe lower end thereof dipped in the liquid fuel present in saidvaporizing plate, said auxiliary burner being composed of side partitionwalls extending radially from both sides of the air supply holes in saidouter cylindrical cover towards said outer peripheral wall and definingan opening in the proximity of said outer peripheral wall and an upperpartition wall covering the top ends of said side partition walls, and.an ignition opening formed in said burner pot outer peripheral wall inopposed relation to said wick.

References Cited UNITED STATES PATENTS 2,388,908 11/ 1945 De Lancey.2,535,923 12/1950 Hill. 2,688,999 9/ 1954 Van Tubergen. 2,822,866 2/1958Miller et al. 3,017,924 1/ 1962 Jenson.

FREDERICK KETTERER, Primary Examiner.

US. Cl. X.R.

